The present invention is particularly applicable for use in controlling the arc of an arc welder driven by a D.C. power supply in the form of an inverter or down chopper. Such welders, especially when operated in the MIG mode, require a large inductor to provide a soft arc. However, in a D.C. welder using a chopper or inverter, the desired current waveforms at the arc can be provided when using a relatively small inductor. Thus, these prior welders do not provide a soft arc to prevent spatter when the waveform is critical. The arc characteristics of the D.C. welders are often controlled by the size of the choke and are not optimized, especially between short circuit conditions in a MIG welding cycle. Thus there is a need for a D.C. welder of the chopper or inverter type which controls the characteristics of the arc without need for a large choke that is detrimental to the waveform.